WDPN32 PGTW 300900
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TROPICAL STORM 19W (JEBI)         
WARNING NR 016//
RMKS/
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.

SUMMARY:
   INITIAL POSITION: 27.9N 140.6E
   INITIAL INTENSITY: 40 KTS
   GEOGRAPHIC REFERENCE: 446 NM SOUTH OF YOKOSUKA, JAPAN
   MOVEMENT PAST 6 HOURS: NORTHWARD AT 13 KTS
   SIGNIFICANT WAVE HEIGHT: 18 FEET

SATELLITE ANALYSIS, INITIAL POSITION AND INTENSITY DISCUSSION:
ANIMATED MULTISPECTRAL SATELLITE IMAGERY CONTINUES TO REVEAL IMPROVING 
OUTFLOW, ESPECIALLY OVER THE WESTERN SEMICIRCLE, WITH CLOUD FILAMENTS 
ALONG THE WESTERN EDGE OF THE CONVECTION, AND ENHANCED POLEWARD 
VENTING INTO THE WESTERLIES TO THE NORTH. THIS HAS ALLOWED THE SYSTEM 
TO CONSOLIDATE QUICKLY WITH TIGHTLY CURVED CONVECTIVE BANDING WRAPPING 
INTO A BETTER-DEFINED LOW-LEVEL CIRCULATION CENTER (LLCC). IN GENERAL, 
SUBJECTIVE DVORAK ESTIMATES REMAIN A BIT LOW, WITH OBJECTIVE ESTIMATES 
BETTER REFLECTING THE IMPROVED CONVECTIVE STRUCTURE. THUS, THE INITIAL 
INTENSITY IS ASSESSED AT 40 KNOTS JUST ABOVE THE HIGHER SUBJECTIVE 
DVORAK ESTIMATES, CLOSER TO THE CIMSS SATCON ESTIMATE OF 43 KNOTS AND 
AIDT ESTIMATE OF 38 KNOTS. THE INITIAL POSITION IS BASED ON THE MSI 
WITH MEDIUM CONFIDENCE. 

INITIAL WIND RADII BASIS: OBJECTIVE BEST TRACK 

CURRENT STEERING MECHANISM: LOW- TO MID-LEVEL SUBTROPICAL RIDGE
POSITIONED TO THE EAST, WITH RIDGE EXTENDING POLEWARD

AGENCY DVORAK AND AUTOMATED FIXES: 
   PGTW: T2.5 - 35 KTS
   RJTD: T2.5 - 35 KTS
   RCTP: T1.5 - 25 KTS
   KNES: T2.5 - 35 KTS
   CIMSS SATCON: 43 KTS AT 300500Z
   CIMSS ADT: 37 KTS AT 300610Z
   CIMSS ADT: 38 KTS AT 3000740Z

FORECASTER ASSESSMENT OF CURRENT ENVIRONMENT: FAVORABLE
   VWS: 5-10 KTS
   SST: 28-29 CELSIUS
   OUTFLOW: MODERATE POLEWARD AND EQUATORWARD

ANALYSIS CONFIDENCE:
   INITIAL POSITION: MEDIUM
   INITIAL INTENSITY: MEDIUM
   INITIAL WIND RADII: LOW

3. FORECAST REASONING.

SIGNIFICANT FORECAST CHANGES: THERE ARE NO SIGNIFICANT CHANGES TO
THE FORECAST FROM THE PREVIOUS WARNING.

FORECAST DISCUSSION: BASED ON THE IMPROVED ENVIRONMENTAL CONDITIONS
PREVIOUSLY DISCUSSED, TS 19W IS EXPECTED TO INTENSIFY TO MINIMAL 
TYPHOON STRENGTH OVER THE NEXT DAY, WITH A PEAK INTENSITY OF 65 KNOTS 
NEAR TAU 24. THE TRACK FORECAST IS RELATIVELY STRAIGHT-FORWARD, WITH A 
NORTHWARD TRACK THROUGH TAU 24 ALONG THE WESTERN PERIPHERY OF THE STR. 
AFTER TAU 24, THE SYSTEM WILL BEGIN TO INTERACT WITH AN UPPER-LEVEL 
SHORTWAVE TROUGH AND WILL COMMENCE EXTRA-TROPICAL TRANSITION (ETT). AS 
THE SYSTEM RECURVES NORTHEASTWARD AROUND THE STR AXIS, IT WILL TRACK 
UNDER THE JET AND GAIN FRONTAL CHARACTERISTICS, COMPLETING ETT BY TAU 
48. STEADY WEAKENING FROM TAU 24 TO TAU 48 IS EXPECTED AS THE SYSTEM 
ENCOUNTERS STRONG VERTICAL WIND SHEAR AND TRACKS OVER COOLER SST 
VALUES. TS 19W WILL MAINTAIN A RELATIVELY COMPACT REGION OF GALE-FORCE 
WINDS, PRIMARILY LOCATED OVER THE EASTERN SEMICIRCLE, AS IT PASSES 
EAST OF THE KANTO PLAIN.        

MODEL DISCUSSION: IT SHOULD BE NOTED THAT THE CPA TO YOKOSUKA HAS
DECREASED GRADUALLY OVER THE PAST 24 HOURS FROM 154NM TO 123NM ON
THE CURRENT FORECAST. THIS UNCERTAINTY, WHICH HAS BEEN MENTIONED ON
PREVIOUS PROGNOSTIC REASONING MESSAGES CONTINUES PRIMARILY DUE TO
UNCERTAINTY IN THE INITIAL POSITION. THE 291800Z ECMWF ENSEMBLE
(EPS) SHOWS A TIGHT GROUPING OF SOLUTIONS BUT CLEARLY SHOWS SOME
UNCERTAINTY IN THE EXACT TRACK, WHICH COULD LEAD TO SOME MINOR
FLUCTUATIONS IN THE CPAS OVER THE NEXT DAY. THE 300000Z GFS
ENSEMBLE (GEFS) SHOWS A WIDER SPREAD OF SOLUTIONS, WITH 2 SOLUTIONS
TRACKING THE SYSTEM OVER THE COASTAL REGION EAST OF YOKOSUKA.
HOWEVER, THE BULK OF THE GEFS SOLUTIONS ARE FURTHER OFF THE COAST.
DETERMINISTIC GUIDANCE COMPRISING THE JTWC TRACK CONSENSUS (CONW)
ALSO SHOWS A TIGHT GROUPING OF MODELS OVER WATER EAST OF YOKOSUKA,
WITH A CROSS-TRACK SPREAD OF 72NM AT TAU 24.         

FORECAST CONFIDENCE:
   TRACK 0 - 72 HR: HIGH
   INTENSITY 0 - 72 HR: MEDIUM//
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